I found an interesting post on Gotfag recently about how widescreen in OpenGL games may require a higher DPI setting on the Y axis.
http://www.gotfrag.com/cs/forums/thread/415245/
Here's some information copied from the post:
"Gaming mice and mice in general were designed for 4:3 aspect ratio especially when it comes to openGL games. This can be problematic when going widescreen and using the full widescreen native resolution the aspect ratio is 16:9 or 16:10. Its clearly evident there is a stretch factor involved so first off you require to know if your widescreen is a 16:9 or 16:10 monitor.
Calculations:
16:9 = (4)(4) : (3)(3) ------> with respect to the 4:3 ratio
16:10= (4)(4) : (3)(3.33) ----> with respect to the 4:3 ratio
What this tells us is that the X axis is stretched far more than the Y axis � I could go into more math as to how to solve this but I think ill skip this part and show what you should set your �Set Point� options to in order to solve this problem.
The fix
1) Once in the �Set Point� gaming options, uncheck the �Link X/Y resolution settings�
2) Change the X-axis dpi and Y-axis depending on the DPI that you use, here are the numbers you might find useful:
Playing on 1800DPI
For 16:9 ratio Set X-axis dpi to 1800 and Y-axis Dpi to 2000 dpi
For 16:10 ratio Set X-axis dpi to 1800 and Y-axis Dpi to 1950 dpi
Playing on 800DPI
For 16:9 ratio Set X-axis dpi to 800 and Y-axis Dpi to 1000 dpi
For 16:10 ratio Set X-axis dpi to 800 and Y-axis Dpi to 950 dpi
Playing on 400DPI
For 16:9 ratio Set X-axis dpi to 400 and Y-axis Dpi to 600 dpi
For 16:10 ratio Set X-axis dpi to 400 and Y-axis Dpi to 550 dpi
3) Once done hit apply and try it out.
In general you want to keep your X-axis dpi at the level you intend to play at while depending on if it was a 16:9 or 16:10 aspect monitor you would up your Y-axis dpi by 200 or 150 respectively. I hope this helps those who enjoy the benefit of playing on the native resolution of their widescreen, enjoy. "
Credit to Emilk for the post.
This makes sense to me. Ever since switching to widescreen my aim has got worse in older games that I still play actively. This may be the solution.
However, which mice on the market can set the X and Y axis DPI separately? I know the G9x can but I'd rather not use it because of the positive accel.